COMPARATIVE SIGNAL INTENSITY MEASUREMENTS IN DYNAMIC GADOLINIUM-ENHANCED MR MAMMOGRAPHY

Increases in signal intensity enhancement were measured in defined reg ions of interest (ROIs) to allow distinction between malignant and ben ign tumors with dynamic gadolinium-enhanced magnetic resonance (MR) ma mmography. Twenty patients with palpable breast lesions (15 malignant, five benign) underwent MR mammography. The dynamic gradient-echo sequ ence was performed with intravenous bolus injection of gadopentetate d imeglumine and consisted of 25 images with a time resolution of 30 sec onds. Contrast enhancement was calculated by comparing user-defined RO IS on pre- and postcontrast images. An increase in signal intensity of 70% or more on the 1-minute postcontrast image was used as the criter ion of malignancy. MR mammograPhic results correlated with histopathol ogic findings in all patients when the defined ROI was in the most enh ancing part of the tumor. For the ROI in areas of submaximal enhanceme nt or when the ROI surrounded the whole lesion, only five and nine tum ors, respectively, fulfilled the malignancy criterion. All malignant t umors showed large variations in signal intensity enhancement that dep ended on the position of the ROI in the tumor. Dynamic, gadolinium-enh anced MR mammography allows distinction of benign from malignant breas t tumors when the selected ROI is in the most enhancing part of the le sion.